The present invention refers to a device for fast changing of parts of the guide for the continuously cast product, hereinafter referred to as bar, and in particular to a device that enables at least some parts of the bar""s guide to be changed in a fast and safe way in continuous-casting plants, advantageously but not exclusively connected directly to a rolling line; the invention also refers to a process for said fast change utilising the device mentioned above.
Continuous-casting lines have for some time now replaced ingot casting in metallurgy, and in particular iron metallurgy, for the production of the so-called flat and long products, with numerous advantages linked, for example, to fewer processing rejects, a more homogeneous quality of the products, and greater productivity of the plants.
More recently, the so-called continuous-rolling technique has begun to assert itself, according to which the semi-finished product or bar, instead of being extracted from the continuous casting machine, sent to a parking area to await subsequent processing, cooled, checked for the presence and elimination of surface flaws, re-heated and finally hot-rolled, is sent from the continuous-casting plant to the rolling plant, either directly or after prior temperature maintenance and equalization treatment. Obviously, continuous rolling brings further advantages in terms of productivity and energy saving.
But along the above advantages, numerous drawbacks or technical requirements may arise that nullify the advantages obtained. For instance, both the natural wear of the bar guide and its damage due to accidents, such as liquid steel spilling due to bar breakdown, or the need to change the dimensions of the cast and/or the ingot mould impose stoppages of the continuous-casting plant and frequently also of the rolling plant.
Numerous solutions to the problem of replacing the bar guide as output from the ingot mould have been proposed; a first one consists in using a number of casting lines so as to ensure having at least one line always operating The British Patent No. 1 243 757 describes a plant in which two assemblies, each comprising a casting ingot mould and guides for the cast body, may be displaced transversely so as to set one of the assemblies alternately in line with a railing mill. In the same way, in the French Patent Applications 2 126 924 and 2 334 448, plants are described comprising two mobile stations, each bearing an ingot mould and at least part of the guide connected to the ingot mould, said stations being mobile transversely so as to be positioned, respectively, inside and outside the casting area.
Such solutions are, obviously, costly and complex, and frequently not suitable for many small and medium-to-small industrial situations. It has also been proposed, in the Italian Patent No. 1 214 180 in the name of the present applicant, to set up beforehand just one second guide for the continuously cast product, which can replace the guide currently being used, when this is either damaged or worn Out. In the patent cited, however, no means and/or processes are indicated for carrying out a fast change.
In any case, the setting-up of a second complete guide is a costly solution, albeit not as costly as the solution that envisages a number of casting lines.
The present invention proposes to get round the drawbacks referred to above by supplying a device used in the continuous casting of metals for fast replacement of at least part of the bar guide.
The present invention also proposes to provide a process for fast changing of at least part of said guide.
According to the present invention, in a continuous-casting plant comprising a casting station, an assembly made up of segments for guiding and cooling the bar, and an assembly for extracting and straightening the bar itself, a device for fast changing of the bar guide is provided which comprises a first station and a second station, at least one of which is provided with displacement means, for example on rails, designed to displace the station and set it in line with the other station when a replacement is to be made, the first of said stations bearing the guide consisting of segments of bar guide, to be replaced either partially or totally, the said segments being linked to a supporting structure, and the second of the said stations bearing a platform provided with means for hooking and extracting the segments of the guide. The fast-changing device also comprises means of positioning of the guide with respect to the ingot mould and means of hooking and translation of the guide from one of the stations to the other.
Alternatively, both of the stations may be mobile. Another possibility is for there to be two stations provided with platform and means for hooking and extraction of the guide segments, both stations being mobile or fixed.
The mobile station (or the set of mobile stations) can be mounted on rectilinear or curved rails so as to move parallel to one another or turn between the casting position and the position in line with the station that receives the guide segments. In a continuous-casting plant comprising an ingot mould connected to oscillating means (or oscillator) and set above a line for guiding the bar extracted from the ingot mould, the process for replacement of the bar guide according to the present invention comprises in sequence and combination, in a relation of co-operation, the operations of (i) setting up a first station and a second station, at least one of which being mobile, the first of the said stations comprising the guide consisting of segments of bar guide, to be replaced, the segments being hooked to a supporting structure, and the second of said stations having a platform equipped with means for hooking and extracting the guide segments; (ii) detecting the need for replacing at least part of the guide segments; (iii) translating said mobile station to align it head on with the other station; (iv) displacing the guide segments from the first station to the second station; (v) replacing at least part of the said guide segments; (vi) displacing said segments partially or totally replaced into the original station; (vii) bringing back the plant into the original working position, i.e., with the guide aligned both to the ingot mould and to the extraction and straightening assembly. The mobile station may be moved by displacing it transversely with respect to its own longitudinal axis, or else by rotating it.
Being in the position for changing the guide segments, the mobile station aligned head on with the fixed station, the guide segments are extracted from the bottom of the station containing them, one after another (and shifted to the empty station), so as to facilitate their further inspection and dismantling.
As an alternative to what is described above, the ingot mould may be displaced together with the guide. In addition, ale the oscillator may be displaced together with the ingot mould.